Electric incandescent lamp bulb for vehicle lamps



arch 1946- R. K. BRAUNSDORFF ET AL 2'396'674 ELECTRIC INCANDESCENT LAMP BULBS FOR VEHICLE LAMPS Filed March 19, 1943 INVENTOR REGINALD/KBRA -f LOR/N Cu 4M M r HT/S M ymmfi ATTORNEYS Patented Mar. 19, 1946 ELECTRIC INCANDESCENT LAMP VEHICLE LAMP S BULB FOR Reginald K. Braunsdorfl, East Orange, and Lorin Curtis, Verona, Lamp Works, Inc., of Delaware N. 1., assignors to Tung-Sol Newark, N. J., a corporation Application March 19, 1943, Serialllo. 479,736

10 Claims. The present invention relates to lamp bulbs and more particularly to light bulbs used on vehicles,

and comprises an improved bulb of this character which will withstand relatively hard duty, as for example, on military cars and trucks.

In the use of conventional headlight bulbs on vehicles subjected to rough usage such as military cars, trucks and tanks. the breakage and failure of the filaments of the bulbs are unduly large. Road shock, gun shock and vibration incidental to gear mechanism are transmitted in some proportion to the filaments and this is accentuated when the lamp bulbs are rigidly soldered into reflectors or metal cans which are rigidly bolted to the vehicle frame, such that the shock to which the military vehicle may be subjected is transmitted through the assembled mechanism and ultimately through the support wires to the filaments. n tests this breakage has in some instances been as high as 50%. The underlying cause of filament failure is somewhat obscure but it is probable that the breakage is due in large part to the filaments becoming somewhat fragile from crystallization during burning which is characteristic of metallic filaments generally, and tungsten in particular, and this theory is supported by the fact that the fracture of the filament often occurs when the filament is cold and unlighted and particularly after the filament has been previously burned.

One object of the present invention is to provide a headlamp bulb in which the breakage of the filament or filaments is substantially reduced.

A further object of the invention is to' produce such improved bulb without unduly adding to the cost of manufacture thereof. 1

'More particularly we have found that by providing for limited free fiexing movements of the support wires and the entire filaments as units in directions at right angles to the filament lengths, a very substantial improvement results in that the breakage or failure of the filaments is very substantially reduced in percentage and further that this may be effected by the structuresdescribed below and without appreciably interfering with the optical functional relationship between the reflectors and the filaments.

For a better understanding of the invention and of the preferred embodiment thereof, reference may be had to the accompanying drawing of which- Fig. 1 is a perspective view of a lamp bulb embodying the invention and representing one embodiment thereof;

Fig. 2 is an enlarged side view of a part of the structure of Fig.

1, showing the supporting structure for the major filament;

Fig. 3 is a view similar to Fig. 2 but illustrating another embodiment of the invention; and

Fig. 4 is a sectional view taken along the line 4-4 of Fig. 3.

In Fig. 1 the improved lamp is shown as comprising the conventional glass envelop 2 having the press 4 and mounted in the base 6. The major filament comprising the straight coil 8 is mounted at its ends on the nickel support wires l0, and the minor filament l2 has its ends clamped by flattened ends of nickel support wires I4 and I5 of which wire I4 is secured to one support wire In and the wire I5 is secured to a third support wire It. In accordance with this embodiment of the invention, the nickel wires I0, instead of extending down into the press 4 as in the conventional structure, are welded, as indicated at l8, to the ends of the Dumet sealing-in wires 20, above the press 4. We have found that this arrangement by which the relatively large nickel support wires I0 are secured to the smaller wires 20 above the press instead of within the press, imparts to the support structure of the major filament 8 a limited free resiliently flexing movement of the support wires Ill and the filament 8 as a unit in directions at right angles to the length of the filament and substantially reduces the breakage as compared with the conventional bulb. As shown best in Fig. 2, the other ends of the wires 20 are joined as usual within the press 4 by weldings 22 to the copper lead-in wires 24 for the base 8. In the particular bulb illustrated in Fig. 1, the support wire l6 for the minor filament i2 is likewise secured to the sealing-in wire I! above the press 4.

In the embodiment of the invention illustrated in Figs. 3 and 4, the nickel support wires ill for the major filament 8 are secured to the Dumet wires 20 within the press by the welds l8 as in the conventional structure, and limited free resilient flexing movements of the support wires to and the filament 8 as a unit in a direction at right angles to the filament length is effected by pinching or otherwise flattening the wires as indicated at 26. As shown best in Fig. 4, the pinching of the wires at 26 provides fiattened surfaces which are in planes parallel to theplane passing through the longitudinal axes of the wires. This local flattening of the support wires ill of the embodiment of Figs. 3 and 4 has been found very effective in reducing the breakage of major filament. The cold working incident to the pinching or flattening operation to form the direction indicated so as to interrupt the flow or the shocks imparted to the bulb.

with the usual operating position of the headlamp reflectors mounted on vehicles, the bulbs are disposed with their axes and their filaments in horizontal planes, and the invention, as measured by severe factory vibration tests, has reduced the premature breakage substantially and on the average to less than and in some instances premature breakage has been completely eliminated.

From the standpoint of manufacture the arrangement of Figs. 1 and 2, which requires no additional operational step, is preferred.

The following is claimed:

1. In a lamp or the character set forth, the combination comprising a press, a coiled malor filament, a minor filament and a support structure for said filaments, said support structure including a pair of support wires projecting from the press and forming the sole support for said major filament and both of said wires being reduced in dimension at a point intermediate the press and the major filament to increase the resistance of the major filament to fracture.

2. A two-filament stop and tail lamp comprising in combination a bulb, a straight coiled major filament and a minor filament therein, a press and structure mounted on said press and supporting said filaments, said support structure including a pair of sealing-in wires secured in the press and extending thereabove, a pair of spaced vertically disposed wires secured at one end to the major filament and welded at their other ends above the press to the ends of the sealingin wires, the diameter of each of said sealing-in wires being less than that of each of said spaced wires. 1

3. A two-filament stop and tail lamp comprising in combination a bulb, a straight coiled major filament and a minor filament therein, a press and structure mounted on said press and supporting said filaments, said support structure including a pair of sealing-in wires secured in the press and extending thereabove, a pair of spaced vertically disposed wires secured at one end to the major filament and welded at their other ends above the press to the ends of the sealingin wires, the diameter of each of said sealing-in wires being less than that of each of said spaced wires, said support structure including a third sealing-in wire secured in the press and extending thereabove, a third support wire secured to said third sealing-in wire above the press,,and means secured to one of said spaced wires and said third support wire for supporting said minor filament, v l

4. The method of reducing breakage of the major coil filament of a stop and tail lamp having a major and a minor filament which comprises locally reducing the support structure of the major filament in dimension intermediate the press and the major filament so as to minimize the transmission of shocks to said filament through the support structure.

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, ment and wires about saidsections generally at 4 length.

right angles to the filament length .and minimizing the transmission of rupturing shocks to said filament through the support wires.

6. In a miniature electric incandescent bulb for vehicle lighting, a press, a coiled metallic filament and support wires for said filament extending from said press, each of said support wires having a flattened section intermediate its length, the plane of the'flattened sections being disposed parallel to the plane of the filament 7. In a miniature electric incandescent lamp, a press, a metallic coiled filament and a pair of parallel support wires for said filament extending from said press, said support wires being flattened in the common plane of the wires at points intermediate their length and equidistant from the press.

8. In a miniature electric incandescent lamp bulb for vehicle headlamps, a metallic coiled filament, a press and support wires for said filament projecting from the press and forming the sole support for the filament, each of said support wires comprising a relatively rigid part to which the filament is fastened and a resiliently flexible section intermediate the rigid part and the press having limited flexing movements of the rigid portions of the support wires and the filament as a unit, in a direction generally at right angles to the filament length, minimizing the transmission of shocks to the filament. l

9. In a miniatureelectric incandescent lamp bulb for vehicle headlamps, a metallic coiled filament, a press and support wires for said filament projecting from the press and forming the sole support for the filament, each oi said support wires comprising a relatively rigid part to which the filament is fastened and a resiliently flexible section intermediate the rigid part and the press having limited flexing movements of the rigid portions of the support wires and the filament as a unit, but only in a direction generally at right angles to the filament length, minimizing the transmission of shocks to the filament.

10. In the manufacture of a miniature electric incandescent lamp bulb for vehicle lighting, comprising a metallic coil filament, a press and a support structure for said filament mounted on said press, the method at reducing premature breakage of the metallic filament from shocks transmitted generally at right angles to the filament length which comprises incorporating in the support structure a section of reduced dimensionto give said support structure and the filament a limited resilient flexing movement in directions generally at right angles to the filament length, within the bulb and spaced from said press.

REGINALD K. BRAUNSDORFF. Loam w. cua'rrs. 

